Additive manufacturing (often referred to as 3D printing) is a process that creates or augments a three-dimensional object by laying down successive layers of material, typically onto a print bed, to form a structure having desired dimensions. Additive manufacturing has become widespread in recent years, and is used to create everything from simple tools to components of complex devices. 3D printers are important tools in this field.
One common use for additive manufacturing is for prototyping. Manufacturing companies create prototypes to determine whether an envisioned product is feasible, practical, and aesthetically pleasing. The practice of “rapid prototyping” has become the standard for many industries. Rapid prototyping allows a business to create a three-dimensional model of a product within hours.
For rapid prototyping, a commonly used additive manufacturing technique is extrusion deposition or Fused Deposition Modeling (FDM). An FDM-capable printer takes a raw material, usually in the form of a filament, extrudes it, heats it until it becomes soft, and deposits the material onto a non-printed platform (known as a print bed) along a predefined path. The material then cures and hardens. After multiple passes along the path, the material accumulates and eventually takes the shape of the desired “model.”
Other types of additive manufacturing include (1) coating, which involves spreading a layer of material over a surface; and (2) pad printing, which uses a pad (often made of silicone) to transfer an image from an etched printing plate that is filled with material (such as ink) to an object.
There are certain structures, however, that are inherently challenging to create using additive manufacturing. One such structure is referred to as an “overhang.” An overhang is a part of a model that is meant to be suspended without any material underneath. An example of an overhang is a bridge. If an overhang is too long, it may sag before the material of the overhang has a chance to cure.
The most common way for 3D modelers to create an overhang is to 3D print an initial structure, commonly known as a “support structure,” onto a print bed, and then to print the overhang on top of the support structure. Examples of printed support structures include an FDM lattice support and a stereolithography (SLA) ‘bed of needles.’ After the model is complete, the modeler removes the support structure material, e.g., by breaking it off or chemically dissolving it.
In some cases, the support structure material can be washed off with water, e.g., a PolyJet™ support structure printed by an Objet™ 3D printer manufactured by Stratasys Ltd. Having to remove the support structure from the model results in wasted material. Additionally, the surfaces remaining after the support structure is removed have a generally rough texture that may need to be smoothed out using an additional process (e.g., polishing).